Evaluation of a 'dipstick' immunoassay to detect cysticercosis in experimentally infected cattle

A 'dipstick' immunoassay for bovine cysticercosis, using an antigen isolated from Taenia hydatigena cyst fluid, was evaluated in cattle experimentally infected with Taenia saginata. The assay correctly identified six out of seven infected cattle, including an animal in which only 12 living cysticerci were found. Cattle became seropositive as early as 3 weeks post-infection. A false-negative reaction was found for one very lightly infected animal, from which only four living cysticerci were recovered at necropsy. The assay was also used to detect circulating antibodies in experimentally infected cattle before and after therapeutic treatment with anthelminthics. The results suggest that praziquantel-treated animals gradually revert to being seronegative after the cysticerci are killed.     

Cerebral cysticercosis in pigs studied by computed tomography and necropsy

An original technique for computed tomography (CT) of the pig's brain is described. Brains of 11 cysticercotic pigs were studied by CT and by macroscopic and microscopic examination after necropsy, in order to compare the tomographic images with the anatomic findings. By CT, cysticerci could be seen in all the brains except one which had only one parasite. Good correlation was found when the CT sections were compared with the anatomic slices, nevertheless not all cysticerci seen during necropsy examination could be identified in the CT images. Only two parasites were found in the ventricles. There were difficulties in differentiating submeningeal and parenchymal localization of the cysticerci. Most cysticerci had similar morphologic appearance; inflammatory reactions of different degrees and characteristics were observed around some of them.     

Host--parasite relationship in cysticercosis: immunologic study in different compartments of the host

Cysticerci parasitize several mammalian species, including man, in which the parasitic disease shows unique characteristics since cysticerci are established mainly in immunologically privileged sites and can survive for many years. The study of the human immune response to cysticerci is helpful in diagnosis and could perhaps also aid in preventing or curing the disease. Anti-cysticercus IgG can be detected in serum and cerebrospinal fluid (CSF) of almost all patients with neurocysticercosis, by the enzyme-linked immunosorbent assay (ELISA); antibodies of the other classes are found less frequently. Antibodies react with up to eight Taenia solium cysticercus antigens, mainly with antigen B. This antigen has an affinity for collagen and is not commonly found in the CSF. It could therefore be participating in vasculitic processes spotted in the brain of neurocysticercotic patients. Immunoglobulins are also identified on the surface of the parasites: IgG is detected on parasites obtained from various tissues; IgM, IgA and IgE mostly on extracerebral cysticerci. We discuss the possibility of extraneural cysticerci being destroyed by the immune response of the host whereas natural aging may cause brain cysticerci death.     

猪囊虫病基因工程疫苗用于免疫治疗的研究

应用猪囊虫病基因工程疫苗分别对实验性猪囊虫病和自然感染的猪囊虫病进行了分组治疗,以探讨该疫苗的免疫治疗作用。１０头人工复制的囊虫病猪,随机分成３组。第１组４头猪,于感染于１个月注射该疫苗,连续３次,间隔１５天;第２组４头猪,于感染后２个月注射疫苗,同上连续３次;第３组２头猪,不注苗。第１组注射疫苗后１个月循环抗原滴度开始降低,２．０、２．５及３．５个月各有１头猪ＣＡ转阴,５个月ＯＤ值分别为０．１４、０．０９、０．１７、０．３８。第２组和第３组各猪血清ＯＤ值一直维持在１．０以上。感染后５个月剖检,第１组４头猪均未检出囊虫;第２组４头猪在咬肌、膈肌、腰肌、股内侧肌、肩胛外侧肌等部位均检测到囊虫,检测部位４０ｃｍ＾２面积发现囊虫３～７个,有部分虫体已钙化,胆汁卵化率为１５．４％;第３组各猪也在各检测部位检测到囊虫,４     

Detection of Taenia solium Cysticercosis in Pigs by ELISA with an Excretory-Secretory Antigen

Serodiagnosis of Taenia solium cysticercosis in pigs was conducted by an enzyme-linked immunosorbent assay with an excretory-secretory antigen. The antigen was obtained by in vitro cultivation of the cysticerci in a synthetic medium RPMI 1640. The sensitivity and specificity of the ELISA in detecting infection in pigs reared on free range was 92% and 100%, respectively. In addition, 33.33% of pigs in which infection could not be detected at meat inspection were found positive by ELISA. However, none of the sera from a group of farm-reared pigs were positive. No cross reactions were observed in pigs that contained either the cysticerci of Taenia hydatigena or hydatid cysts.     

Serological diagnosis of cysticercosis by an enzyme-linked immunosorbent assay in experimentally infected cattle.

Taenia saginata infections were established in four groups of calves by administering doses of 10, 10(2), 10(3) and 10(4) infective eggs respectively by gavage. A fifth group remained as uninfected controls. Sera were collected from all calves over a period of 210 days. The sera were examined by an enzyme-linked immunosorbent assay (ELISA) with a fraction of larval Taenia hydatigena cyst fluid as antigen for the presence of anti-T. saginata IgG antibodies. At slaughter, the tongue, masseter, diaphragm and cardiac muscles and liver were examined for cysticerci. The higher dose rates of T. saginata eggs were reflected in higher numbers of cysticerci found in the calves at necropsy. There was also a correlation between higher levels of antibodies produced as measured by the ELISA and the numbers of eggs given. Sero-conversion was first detected about 25 days postinfection in heavy infections and later in the lighter infections. Maximal levels of antibody occurred between 40 and 60 days postinfection, followed by a gradual decrease in levels of antibody. A secondary increase in antibody occurred between 160 and 200 days postinfection which might have been due to release of antigen after death of the cysticerci. The low level of circulating antibodies in light infections may result in false positive or false negative diagnoses depending upon the selection of the cut-off point.     

猪囊虫病基因工程疫苗的研制

从猪带绦虫六钩蚴ｃＤＮＡ文库中筛选目的基因并进行克隆表达,重组抗原用血清学方法和猪体免疫进行鉴定。钭具有免疫保护作用的重组抗原纯化,与免疫刺激复合物疫苗佐剂混合,制备成猪囊虫病基因工程疫苗,免疫仔猪并攻虫。该疫苗安全,无毒副作用,免疫猪减虫率９２．２％,完全保护率５５．５％,且免疫组发现的囊虫多数已死亡。     

Histopathological and histoenzymatic studies on experimental Taenia saginata cysticercosis

In young Taenia saginata cysticerci the reactions for alkaline phosphatase (AlPh), acid phosphatase (AcPh), ATP-ases, succinic dehydrogenase (SDH) and lacto dehydrogenase (LDH) were mild. The reactions were concentrated in the walls of spiral canals (AlPh, SDH) and in the outer layer of the bladder (AlPh). The reactions were more intensive in older cysticerci. In these, the reaction of AlPh marked a network of blood vessels winding around the larva. In dying cysticerci the reactions for oxidative enzymes (SDH, LDH) were weaker but the activity of the hydrolytic enzymes (AlPh, AcPh) was increased. These findings suggest that histoenzymatic reactions may be helpful in determining the viability and the age of cysticerci. T. saginata cysticerci in sheep and goats provoked an early and intensive cellular reaction. The histopathological appearance of the cysticerci as they were destroyed in the abnormal hosts was similar to that of cysticerci localized in abnormal tissue of the natural host (e.g., lung of calves). Treatment with mebendazole caused an intensive infiltrative reaction against dying cysticerci and a degenerative process in the surrounding muscle tissue. The treatment with praziquantel provoked a weak infiltration around dead cysticerci and did not affect the muscle tissue. In both cases the remnants of T. saginata cysticerci disappeared very slowly.     

Cerebral cysticercosis by Taenia crassiceps in a domestic cat.

Cerebral cysticercosis by Taenia crassiceps was diagnosed in an adult female domestic shorthair cat. The animal was euthanized 6 weeks after the initial presentation with signs of vomiting, lethargy, and ataxia. The disease took an intermittent relapsing course with the neurological signs progressing eventually to recumbancy and coma. At necropsy, numerous cysticerci were found in the dilated left lateral ventricle and the adjacent brain parenchyma. The cysticerci were identified as metacestodes of T. crassiceps larvae based on size and morphology of the cysts; shape, number, and size of the rostellar hooks; and mode of proliferation, including endogenous and exogenous budding. Cerebral cysticercosis by T. crassiceps is rare in atypical intermediate hosts and has not been described in cats.     

An outbreak of cysticercosis in feedlot cattle

An outbreak of cysticercosis (infestation with the larvae of Taenia saginata) occurred in feedlot cattle in Ontario in 1986. Two hundred and thirty-three of 271 steers were confirmed histologically to be positive for cysticerci. Nineteen (8.2%) animals had viable cysticerci, 87 (37.3%) had degenerated cysticerci, 77 (33.0%) had mineralized cysticerci, and 50 (21.5%) steers had lymphoid granulomas consistent with cysticercosis. Three viable cysticerci were partly evaginated and one degenerate cysticercus was fully evaginated.     

The effect of corticosteroids on the cysticerci of Taenia ovis in sheep.

The effect of two synthetic corticosteroids on the cysticerci of Taenia ovis in sheep has been investigated. Dexamethasone given from four days before infection had no effect on the number of cysticerci recovered but did enhance their survival. When betamethasone was used there was an increase in the number of cysts compared with controls. Corticosteroids given for 12 days after infection did not increase the number of viable cysticerci recovered at autopsy three months later but when treatment was continued until the time of autopsy, a very high proportion of cysticerci were viable.     

Sero-epidemiological study of Taenia saginata cysticercosis in Belgian cattle

A sero-epidemiological survey of Taenia saginata cysticercosis was carried out to determine the prevalence of the infection in cattle presented for slaughter in Belgium. Between November 1997 and June 1998, a total of 1164 serum samples were collected in 20 export abattoirs. Meat inspection was routinely carried out by veterinary inspectors. Serum samples were examined for circulating parasite antigen using a monoclonal antibody-based sandwich enzyme-linked-immunosorbent assay (Ag-ELISA). Thirty six serum samples (3.09%) were found positive in the Ag-ELISA, while by meat inspection on the same animals cysticerci were detected in only three carcasses (0.26%). Sero-prevalence was positively correlated with the age of the animals. The sero-prevalence found in this study was more than 10 times higher than the annual prevalence (0.26%) reported by the Institute for Veterinary Inspection. This study clearly indicates that the classical meat inspection techniques detect only a minor fraction of the carcasses infected with cysticerci.     

Kinetics of circulating antigens in pigs experimentally infected with Taenia solium eggs

Three groups of four piglets were experimentally infected with different doses (10(3), 10(4) and 10(5)) of Taenia solium eggs whereas a fourth group of two pigs received gravid proglottids. At autopsy 6 months post infection, the two latter pigs were heavily infected with more than 3000 living cysts per kg of muscle. Ten of the 12 other pigs harboured light infections, i.e. between 2 and 107 cysticerci, 42.4% of which were degenerated. The two remaining pigs had no detectable cysts at post mortem examination. Circulating antigens (CA) were detected in the sera of all pigs harbouring living cysticerci using a monoclonal antibody based ELISA. CA were first detected between 2 and 6 weeks post infection and remained present generally throughout the entire observation period even in pigs carrying only five to eight living cysts, although strong fluctuations of the level of CA were observed in some pigs. In animals without living cysts at post mortem CA were only detected for a short period and disappeared presumably when the cysticerci became degenerated. The minimum number of living cysts, which could be detected using this ELISA, was 1.     

Freezing times and temperatures required to kill cysticerci of Taenia saginata in beef

Calves were given viable Taenia saginata eggs by stomach tube and slaughtered 12, 16 or 24 weeks later. The cysticerci-infected carcasses were frozen at six different temperatures for variable lenghts of time. Meat samples were then allowed to thaw at room temperature and the cysticerci were manually isolated. Criteria of viablity of the metacestodes were scolex evagination and peristaltic movements of the bladder wall. Sixteen and especially 12-week-old cysticerci were much more susceptible to the lethal effects of freezing than were 24-week-old cysticerci. The time and temperature combinations required to ensure death of all cysticerci were 360 h at ?5°C, 216 h at ?10°C, and 144 h at ?15°C or lower.     

Generalized Taenia crassiceps cysticercosis in a chinchilla (Chinchilla lanigera)

Taenia crassiceps is a cestode parasite that uses carnivores as definitive hosts and rodents and rabbits as main intermediate hosts, but other animal species and humans may also get infected. One adult male chinchilla (Chinchilla lanigera) from an animal shelter in Switzerland presented widespread subcutaneous fluctuant swellings extended over the forehead, nose, face and thoracic regions with a progressive growth over 3 months. The thoracic swelling was surgically resected, and it consisted of numerous 3–4 mm small transparent vesicles, mainly confined to the subcutaneous tissue, which were morphologically identified as cysticerci of T. crassiceps. The diagnosis was confirmed by PCR and DNA sequence analysis of fragments of the mitochondrial small subunit rRNA and NADH dehydrogenase subunit 1 genes. After 1.5 months, due to enlargement of the swollen areas and deterioration of the general health condition, the chinchilla was euthanized and a necropsy was performed. Thousands of small cysticerci were observed widespread in the subcutis, involving underlying musculature of the whole body, in the thoracic cavity, larynx, pharynx and in the retropharyngeal region. Additionally, three larger metacestodes were detected in the liver and morphologically and molecularly identified as Taenia taeniaeformis strobilocerci. The present case represents an indicator of the environmental contamination with Taenia eggs, highlighting the risk of infection for susceptible animals and humans. Besides the clinical relevance for pets, T. crassiceps is a zoonotic parasite and can be also cause of severe cysticercosis in humans.     

Morphological changes to early stage Taenia solium cysticerci following oxfendazole treatment

The progressive morphological changes to early stage Taenia solium cysticerci following the treatment of pigs with a single therapeutic dose of oxfendazole (30 mg/kg), are described. On Day 1 after treatment, no obvious changes occurred in the general appearance of the larvae but alternations were seen by electron microscope, with an apparent reduction in the number of microtriches, and a complete disappearance of the tegument. Numerous granules were seen to have accumulated in the tegument cells. As treatment progressed, damage to the cysticerci was more serious and, by five days, all cysticerci were seen to be in an advanced stage of degeneration. By 45 days post-treatment, all cysts were calcified. These results suggest that oxfendazole is a highly effective drug against T. solium cysticerci in the early stages of development.     

In vivo cross-reactivity of Taenia saginata and Taenia crassiceps antigens in bovine cysticercosis

Steers sensitized or infected with Taenia saginata exhibited similar delayed-type dermal hypersensitivity (DTH) responses after intradermal inoculation with T. saginata or T. crassiceps skin test antigens. Steers sensitized to T. crassiceps cysticerci exhibited similar DTH responses to intradermal inoculation with T. crassiceps, T. saginata whole worm and T. saginata cysticerci antigens. No correlation existed between the DTH responses and the number of cysticerci in the carcasses. One sensitized/infected and one infected steer harbored cysticerci but exhibited no DTH responses. Infection with cysticerci did not elevate DTH responsiveness in sensitized animals.     

Oncospheres of Taenia solium develop into cysticerci in normal mice

In vitro-hatched oncospheres of Taenia solium, prepared by the sodium hypochlorite method and adjusted to approximately 5 x 10(2)/2ml phosphate buffer saline, were injected intramuscularly or intravenously into normal Balb/c mice. When these mice were sacrificed 2 months later, all cysticerci were exclusively recovered in the lungs from the mice with intravenous inoculation, but not with intramuscular injection. A high infection rate of 76% was obtained and a total of 45 cysticerci were collected from 50 mice. Thirty-five cysticerci were mature and with normal appearance but the rest were either with abnormal appearance (4) or degenerated (6). These findings give strong evidence that T. solium oncospheres may migrate to the normal mouse lung through venous circulation and develop in this organ.     

Prevalence of bovine cysticercosis and hydatidosis in Jimma municipal abattoir, South West Ethiopia

A cross-sectional study to determine the prevalence of bovine cysticercosis and hydatidosis was conducted from October 2007 to March 2008 in cattle slaughtered at the Jimma municipal abattoir. Cyst distribution and viability of bovine cysticercosis and hydatidosis were also determined. A total of 512 carcasses were inspected of which 15 (2.93%) and 161 (31.44%) were infected with Taenia saginata metacestodes and hydatid cysts, respectively. From a total of 109 cysticerci collected from infected carcasses, 47 (43.12%) were viable. The anatomical distribution of the cysticerci was, shoulder muscle (39.5%), heart (33.9%), neck muscle (13.8%), tongue (10.1%), masseter muscles (1.8%) and diaphragm (0.9%). Of the 1171 hydatid cysts collected 223 (19.0%) were fertile, 505 (43.1%) sterile, 49 (29.8%) calcified and 94 (8.0%) contained pus. A greater proportion of fertile cysts were found in the lungs than in other organs. It was concluded that these zoonotic cestodes deserve due attention to safeguard public health, and that further studies are needed on genotyping, epidemiology and public health importance of Echinococcus granulosus in the study area.     

The efficacy of mebendazole and praziquantel againstTaenia saginata cysticercosis in cattle

Approximately 50,000Taenia saginata eggs were given orally to bullocks. Ten weeks later, mebendazole or praziquantel was administered in the fodder in single or multiple doses. The animals were slaughtered at intervals after medication when the numbers and viability of cysticerci in various sites were recorded. Single doses of 5 mg/kg mebendazole or 10 mg/kg praziquantel had little effect on the viability of cysticerci. One single dose of 25 mg/kg or 10 daily doses of 5 mg/kg mebendazole had some effect. Praziquantel was completely effective against the viability of cysticerci in either one single dose of 100 mg/kg or 10 daily doses of 10 mg/kg.